The present invention relates to a screen member for a reflex type screen that is simple in structure and superior in optical characteristics.
FIG. 3 shows a conventional screen member for a reflex type screen. A reflex film 21 is bonded by adhesives on a surface made of PET film (polyethylene telephthalate resin film) which serves as a base 20 of the screen. A deflection film 22 made of PETPF film (polyethylene telephthalate resin film system deflection film, more specifically, polyester system deflection plate made by mono-axis drawing and adding two-color dye to polyester resin) is bonded onto a surface of the reflex film 21 by adhesives. An OPP film (bi-axial drawn polypropylene film) is bonded by adhesives on a surface of the deflection film 22 as a random reflective film 23 for reflecting, at random, the reflex beam of light from the reflex film 21 and an incident beam of light from a projecting means such as a projector.
However, in the prior art, a large number (four) of films must be bonded by adhesives to each other. In the case where a large screen such as an 80-inch screen is to be manufactured, it is very troublesome or difficult to bond the films without creases or non-uniformity.
In addition, in the prior art, the surface of the random reflective film 23, which is the frontmost surface layer of the screen member, is formed in a corrugated manner, and the incident ray of light from the projector and the reflective ray of light from the reflex film 21 is reflected randomly so that an image projected on the screen may be observed even in a direction oblique to the screen. However, if the large size screen is designed with such an arrangement, a degree of the random reflection is too small and the image becomes dark if it is viewed in the oblique direction relative to the screen. Thus, image projected on the screen is hardly observed.
Also, the conventional system suffers from the following disadvantages. Namely, the OPP film (random reflective film 23) is a bi-axial drawn film. An axial displacement of the crystal axis is likely to occur in a width direction. The displacement between a transparent axis and the deflection film 22 used in the screen is in the width direction so that particularly, the image at the right and left end portions is likely to be dark.